Two-phase flow system with discrete impinging two-phase jets

ABSTRACT

A flow system with discrete two-phase nozzles is disclosed. The two-phase jets produced in the nozzles are caused to impinge one another in a mixing channel, resulting in significant coalescence of the liquid into a stream in the center of the channel, with the gas in the jet being forced to the periphery of the liquid stream.

FIP'85D2 United States Patent Low et al. 1 Mar. 7, 1972 [54] TWO-PHASE FLOW SYSTEM WITH [56] References Cited I .llgigRETE IMPINGING TWO-PHASE UNTED STATES PATENTS 2,951,554 9/1960 Becker ..55/l7 [721 M- Deputy Admlmsram of 3,158,764 11/1964 Elliot ..310ll1 3g z g s f gg; 3,320,444 5/1967 Prem ..3 10/11 of; David G. Elliott, 5208 North Point 3,525,886 8/1970 Radebold ..3l0/l1 Road, La Canada; Lance G. Hays, 4328 Primary Examiner-D. X. Sllney Cany Attorney-Monte F. Mott, John R. Manning and Paul F. Me- [22] Filed: Oct. 21, 1970 Caul [21] Appl. No.: 82,648 ABSTRACT A flow system with discrete two-phase nozzles is disclosed. 2 {g l big The two-phase jets produced in the nozzles are caused to 1m [58] Field 61 Search II..............: 15/16 11 55715 17 396- We amber in a mixing channel *esumng significam 6 coalescence of the liquid into a stream in the center of the channel, with the gas in thejet being forced to the periphery of the liquid stream.

2 Claims, 3 Drawing Figures SOURCE OF LIQUID AND MHD GENERATOR GAS Patented March 7, 1972 .0 Fumm mmOmO mohdmmzwmv DIE OP 0Ju 0503 SOJu mdw G E 6 BY WWW ATTORNEYS DIE mg 024 0503 no wumaow 1 TWO-PHASE FLOW SYSTEM WITH DISCRETE IMPINGING TWO-PHASE JETS ORIGIN OF INVENTION Space Act of 1958, Public Law 85-568 (72 Stat. 435; 42 USC BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to the formation of a stream of liquid for use in a magnetohydrodynamic (MHD) generator and, more particularly, to the formation of such a liquid stream from two-phase streams.

2. Description of the Prior Art As is appreciated, in a MI-ID electrical power generator, a high velocity stream of metal liquid is required as the source of input power. In such a generator liquid velocities of 300 to 1,000 ft./s. are generally employed. To obtain such high velocities two-phase nozzles are employed. A two-phase nozzle is one in which a liquid and a gas are mixed at high pressure and low velocity and are expanded to low pressure and high velocity. The stream or jet which exits such a nozzle contains a mixture of liquid and gas. For most efficient generator operation the stream supplied thereto should consist of liquid only. Thus, it is necessary to separate the gas from the liquid prior to supplying the latter to the generator.

Herebefore such separation was done by introducing separators in the path of the exit jet. The solid surfaces of the separators are used to deflect the gas, so that the stream,

directed to the generator, consists primarily of liquid.

Although the separators accomplish the desired function, the friction between the liquid and their solid surfaces tends to reduce the liquid velocity, thereby reducing cycle efficiency. The ability to sufficiently concentrate or coalesce the liquid phase and separate it from the gas phase without the use of solid surfaces would account for increased cycle efficiency.

OBJECTS AND SUMMARY OF THE INVENTION It is a primary object of the present invention to provide a new configuration for the separation of gas from liquid in a two-phase flow system.

Another object of the invention is the provision of an arrangement whereby gas is separated from liquid in a twophase flow system without resort to separators with solid surfaces.

These and other objects of the invention are achieved by causing separate jets which exit from a plurality of discrete two-phase nozzles to impinge on each other. It has been discovered that when the jets impinge on each other, the liquid from the jets tends to concentrate or coalesce in the center of the combined stream in the mixing region while the gas phase tends to surround the liquid. Thus, liquid coalesce is achieved without reso to separators with solid surfaces whereat friction is created, which reduces cycle'efficienc'y.

The novel features of the invention are set forth with particulan'ty in the appended claims. The invention will best be understood from the following description when read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a combination block and schematic diagram of an embodiment of the present invention;

FIG. 2 is a diagram useful in explaining the embodiment shown in FIG. 1; and

FIG. 3 is a partial cross-sectional view of another embodiment of the invention.

2 DESCRIPTION OF THE PREFERRED EMBODIMENTS Attention is first directed to FIG. 1 wherein block 10 designates a source of liquid and gas. Connected to source 10 are two discretenozzles l2 and 13, wherein two-phase flow is created in a manner well known in the art. Thus, nozzles I2 and 13 may hereafter be referred to as the two-phase nozzles. The exit ends 14 and 15 of nozzles 12 and I3, respectively are in communication with a mixing channel 20. As is appreciated, thejet which exits a two-phase nozzle is a mixture of liquid and gas, represented in FIG. 1 by broken lines 21 and the small dots 22, respectively.

In accordance with the present invention, the angle between the centerline of each nozzle and the centerline of channel 20 is chosen to cause the two jets 25 and 26 which exit nozzles 12 and 13, respectively to impinge one another. It has been discovered that such impingement causes a sufficiently high concentration or coalescence of the liquid so that a stream of highly concentrated liquid is formed about the center of the channel, while the gas is forced to concentrate between the outer limits of the liquid stream and the channel's walls. In FIG. 1, the combined liquid stream is designated by numeral 30 and the separated gas by numeral 31.

As seen from FIG. 1, the gas 31 is separated from the liquid stream 30 by knife-edged members 32, which deflect the gas into capture channels 33, which in turn direct the gas back to the source 10. The liquid stream 30 is directed to the MHD generator, designated by numeral 35. In practice, the liquid, after passing through the generator, is returned to the source 10.

In practice, the impingement angle and the length of channel 20 are chosen so that the knife-edged members 32 can be located at the neighborhood of the geometric impingement point, which is designated in FIG. 2 by numeral 40. Therein, the impingement angle of each nozzle is designated by a.

Over a range of impingement angles from 5 to 20, the liquid flow is found to be concentrated at the centerline, near the geometric impingement point, to about four times the liquid flow rate per unit area, existing at the exit of the nozzles. The concentration decreases away from the center line. If the knife edges are set to collect 90 percent of the liquid flow, the average concentration of the collected flow is twice that of the nozzle exits; that is, the slot area is half the total nozzle exit area.

From the foregoing it is thus seen that by impinging several discrete two-phase jets on each other, liquid coalescence is achieved without the need for friction-producing separators. Thus, cycle efficiency is increased. Herebefore, the invention has been described in conjunction with two discrete two-phase jet-producing nozzles. It should be stressed that the invention is not limited to a two nozzle arrangement. Rather, it is directed to an arrangement with any number of discrete twophase nozzles.

It is believed that the use of a plurality of discrete nozzles which provide two-phase jets, caused to impinge one another in a mixing channel to coalesce the liquid and separate the gas therefrom, is particularly advantageous for the production of a liquid stream which has a cross section in a direction perpendicular-to the. flow. directionwhich is other than circular. This.

is the case in some MHD power generation applications in which liquid streams with square or rectangular cross sections are desired. Such streams can be produced with optimum efficiency by positioning a plurality of nozzles, e.g., 4, at the inlet end of channel 20, so that the jets exiting from the nozzles in addition to producing liquid coalescence also form the liquid stream of the desired cross section.

FIG. 3 to which reference is now made represents a crosssectional view of the channels inlet end at which the exit ends 41-44 of four two-phase nozzles 45-48 are located. By controlling the relative positions of the exit ends and the cross section of the jets produced in the various nozzles, the cross section of the coalesced liquid stream is easily controllable.

Although particular embodiments of the invention have been described and illustrated herein, it is recognized that modifications and variations may readily occur to those skilled in the art and, consequently, it is intended that the claims be interpreted to cover such modifications and equivalents.

What is claimed is:

1. in combination with a magnetohydrodynamic power generating system, an arrangement for supplying said system with a concentrated stream of high velocity metal liquid, the arrangement comprising:

a source of high pressure low velocity gas and metal liquid;

at least first and second discrete two-phase nozzles each having an inlet end in communication with said source for receiving said gas and said metal liquid therefrom and an exit end at which a jet of high velocity gas and metal liquid exits;

a mixing channel having an inlet end with which said nozzles exit ends are in communication at a preselected angle, whereby the two-phase jets, exiting the exit ends of said nozzles impinge one another, causing coalescence of the metal liquid into a concentrated metal liquid stream about the center of said channel, with the gas on the outside of said stream, with the gas and the metal liquid stream flowing toward the channel's outlet end, said outlet end defining an opening through which said metal liquid stream exits to said power generating system; and

separating means in said channel for removing the gas surrounding said metal liquid stream.

2. The arrangement as recited in claim 1 wherein the exit ends of said nozzles are arranged in a preselected configuration at the inlet end of said channel so that the jets exiting therefrom impinge each other to form a concentrated metal liquid stream with a selected cross section, other than circular, in a direction perpendicular to the streams flow direction. 

1. In combination with a magnetohydrodynamic power generating system, an arrangement for supplying said system with a concentrated stream of high velocity metal liquid, the arrangement comprising: a source of high pressure low velocity gas and metal liquid; at least first and second discrete two-phase nozzles each having an inlet end in communication with said source for receiving said gas and said metal liquid therefrom and an exit end at which a jet of high velocity gas and metal liquid exits; a mixing channel having an inlet end with which said nozzles'' exit ends are in communication at a preselected angle, whereby the two-phase jets, exiting the exit ends of said nozzles impinge one another, causing coalescence of the metal liquid into a concentrated metal liquid stream about the center of said channel, with the gas on the outside of said stream, with the gas and the metal liquid stream flowing toward the channel''s outlet end, said outlet end defining an opening through which said metal liquid stream exits to said power generating system; and separating means in said channel for removing the gas surrounding said metal liquid stream.
 2. The arrangement as recited in claim 1 wherein the exit ends of said nozzles are arranged in a preselected configuration at the inlet end of said channel so that the jets exiting therefrom impinge each other to form a concentrated metal liquid stream with a selected cross section, other than circular, in a direction perpendicular to the stream''s flow direction. 